\begin{tikzpicture}[>=latex,every node/.style={anchor=south west,,inner sep=0,fill=white}]
    \node(Figure1)[anchor=north] at (0,0){  
        \begin{tabular}{|m{1em}<{\centering}|m{1em}<{\centering}|m{1em}<{\centering}|}
            \hline 
             & a & b\\ \hline
            1 & 6 & 3 \\ \hline
            3 & 1 & 5 \\ \hline
            6 & 4 &   \\ \hline
            5 & 7 & 3 \\ \hline
            4 & 4 & 6 \\ \hline
            7 & 4 &   \\ \hline
        \end{tabular}
    };	
    \node  (+1) at([xshift=-4.2em,yshift=-2.2em]Figure1.north) {+};
    \node  (-6) at([xshift=-4.1em,yshift=-4.5em]Figure1.north) {-};
    \node  (-5) at([xshift=-4.1em,yshift=-5.75em]Figure1.north) {-};
    \node  (-7) at([xshift=-4.1em,yshift=-8.25em]Figure1.north) {-};
    \draw ([xshift=-3.25em,yshift=-0.05em]Figure1.north) edge ([xshift=-1.1em,yshift=-1.25em]Figure1.north);
    \draw ([xshift=-0.3em,yshift=-1.875em]Figure1.north) edge [dashed,->,red!20] ([xshift=-1.9em,yshift=-4.375em]Figure1.north);
    \draw ([xshift=1.9em,yshift=-1.875em]Figure1.north) edge [dashed,->,red!20] ([xshift=-1.9em,yshift=-3.125em]Figure1.north);
    \draw ([xshift=1.9em,yshift=-3.125em]Figure1.north) edge [dashed,->,red!20] ([xshift=-1.9em,yshift=-5.625em]Figure1.north);
    \draw ([xshift=-0.3em,yshift=-4.375em]Figure1.north) edge [dashed,->,red!20] ([xshift=-1.9em,yshift=-6.875em]Figure1.north);
    \draw ([xshift=-0.3em,yshift=-5.625em]Figure1.north) edge [dashed,->,red!20] ([xshift=-1.9em,yshift=-8.125em]Figure1.north);
    % \draw (1.9em,-2.8em) edge [dashed,->,red!20] (-1.9em,-4em);
    % \draw (1.9em,-4.3em) edge [dashed,->,red!20] (-1.9em,-7em);
    % \draw (-0.3em,-6em) edge [dashed,->,red!20] (-1.9em,-8.6em);
    % \draw (-0.3em,-7.5em) edge [dashed,->,red!20] (-1.9em,-10em);
\end{tikzpicture}